The purpose of this project is to provide the morphological details of the effects of tooth pulp extirpation, extraction of teeth and exfoliation of deciduous teeth on the trigeminal system and to supply anatomical particulars of the precise pathways from teeth and periodontal structures to the central nervous system (CNS). Light and electron microscopy, both conventional and modern techniques, will be used in qualitative and quantitative investigations in felines and in non-human primates. The acute degeneration and chronic alterations associated with these different types of exodontic and endodontic procedures and of natural tooth loss will be analyzed in the sensory neurons of the trigeminal ganglia, their central axons and synapses in the brain stem trigeminalnuclei. Subjects at various known ages and stages of dental maturity will be used in the study to determine the relationship of age and development to these events. These experiments will also be used to define the specific and individual sites of representation for teeth and periodontal structures in the CNS. Additional experiments are being included to specifically evaluate the possible route of the controversial bilateral tooth projections to brain stem. These degeneration procedures will be supplemented by more modern methods of neuronal and axonal transport to detail the pathways and projections. Although emphasising cats and kittens, similar studies will be extended to non-human primates so that the comparative results may be more directly applicable to humans. The project will be useful in providing new information about the anatomical representation for dental structures within the CNS and will also provide possible morphological explanations for certain sensory alterations, including pain related symptoms associated with dental surgery, endodontic therapy, tooth loss or traum involving these structures.